Scaffold



May 1. 1928.

F. HOFFMANN ET AL SCAFFOLD 2 Sheets-Sheet 1 Filed Feb. 23, 1927 adj May 1.. 1928.

F. HOFFMANN ET AL SCAFFOLD Filed Fe 1927 k 2 Sheets-Sheet 2 Patented May 1, 1928.

UNITED STATES PATENT OFFICE.

SGAFFOLD.

Application filed February 23, 1927. Serial No. 170,091.

Our invention relates to scaffolds such as are used in the construction of tall build ngs, and has for its principal ob ect to provide a scaffold frame which may be readily raised Figure 1 is a side elevation of a scaffold 20 frame embodying our invention,

Figure 2 is an end view thereof, Figure 3 a fragmentary sectional view taken on the line 3-3 on Figure 2, and

Figure 4 a fragmentary view taken on the 25 line 44 on Figure 3.

Figure 5 is a top plan view of one end of the channel forming the bottom of the scaffold frame, and

Figure 6 an end view thereof.

Referring now more in detail to the drawings tl1e scaffold frame is composed of a top strut 10 having bifurcated ends supporting hangers 11, one of which carries a hanger bar-12while the'other carries a hanger cable 13 with a channel 14 supported between their lower ends. A drum 15 is mounted on a shaft 16 rotatable in each hanger 1.1 and carries a cable 17 by means of which the scaffold frame is supported.

A scaffold consists/of tWo or more scaffold frames having planks extending from one to the other and resting on channels 14; the distance between the several frames depending on the nature of'the work too be performed. the load to be carried by the scaffold, and the strength of the planking used. The frames are suspended with cable 13 toward the building in order that the workmen may have asfree access as possible to the work upon which they are engaged.

Top strut 10 is preferably made from two bars having their central portions riveted together and each end bento outwardly, as shown in Figures 1 and 2. Each hanger 11 preferably consists of two bars bent to form a substantially U-shapcd member; the upper end of each bar being connected to one of the bars forming top strut 10, preferably by belts in order that the scaffold frame may be demounted. Cable 13 has one end attached to the lower end of one hanger 11 and its other end secured to one end of channel 14 in any suitable manner, as by means of a casting 18 attached to the under side of channel 14 and provided with an eye 19, extending through a slot 20 in channel 14, to which the end of the cable is secured in a well known manner. One end of casting 18 is provided with rounded corners and extends beyond the end of channel 14 so as to abut the wall should the scaffold swing inwardly, thus protecting the wall from the sharp corners of the channel aswell as protecting the raising mechanism of the scaffold from injury. Hanger bar 12 is secured to the bottom of the other hanger 11 and either the hanger or the bar is given a half turn so that the lower end of bar 12 may be secured to an angle 21 riveted to the other end of channel 14. The ,upper end of cable 13 and both ends of hanger bar 12 are preferably bolted in place in order that the scaffold frame may be fully demountable.

A hook 22 is secured to hanger bar 12 and is adapted to receive a guard rail, such as a piece of 2 by '4 framing, which extends across two or more scaffold frames. A pin 23 is secured in hanger bar- 12 at a point above hook 22 and may be bent in any de' sired shape so that tools or small equipment may be hung thereon for the convenience of the workmen occupying the scaffold.

()ne end of shaft 16 extends through a bearing 24 secured to one side of hanger 11 and has a worm wheel 25 rigidly secured thereon. A worm bearing 26 is secured toor formed on hearing 24 and has a worm 27,

formed on a worm shaft 28, mounted therein and meshing with worm wheel 25. .The distance between the ends of bearing 26 is greater than the length of worm 27 so that it may move axially in the hearing as will be later described. Theinner end of worm shaft, 28 is flattened in order to be straddled by the bifurcated head of a connecting shaft 29 and is connected thereto by a single bolt. The other end of connecting shaft 29 also has a bifurcated head which engages the flattened end of a worm shaft 28 rotatable in a bearing 26" in which is mounted' a worm 27. The ends of shafts 28 and 28 are simllarly flattened and both ends'of shaft 27 are,

endless hand chain 30 which engages a chain wheel 31 secured to shaft 28. Worm 27 is provided with an annular-groove 32 near its outer end while worm 27 is provided with p a groove 32 near its inner end. With the exception of the location of groove 32* and the addition of chain wheel 31, worm 27- and worm shaft 28 are similarto worm 27 and worm shaft 28. r

A ratchet wheel 33, shown as.being formed on one side of worm wheel 25, is engaged by a pawl 34 pivoted on a pin 35 extending from hearing 24. A trip 36, rockably mounted on a pin 37 extending from bearing 24, has one end adapted to engage the under side of a projection 38, formed on the side of pawl 34, while its opposite end is bifur cated and straddles the'reduced portion of worm, 27 formed by groove 32.

In use, the scaffold frame is swung from the building on cables 17 in the usual manner and may be raised by rotating worms 27- by means of hand chain 30. After it is swung free, channel 14 may be leveled by disconnecting shaft 29 from one'of the worm shafts and rotating worm 27. The shafts are then reconnected and, by rotating worm wheels 25 in an anti-clockwise direction, the scaffold frame will be raised, pawl 34 riding over the notches in ratchet wheel 33. YVhen the desired height has been reached, a slight re 39 of bearings 26 and 26, thus moving thebifurcatcd end of trip 36 and releasing pawl 34, which will drop into one of the notches in ratchet: wheel 33 and-remove the'strain from the worms and teeth of the worm wheel as well as prevent drums 15. from turning and allowing the scaffold to work downwardly.

When hand chain 30 is operated to lower the scaffold, the worms will move axially in the worm bearings sufliciently to move the upperends of trips 36 and thus raise'pawls 34 away from ratchet wheels 33; which movement simultaneously transfers the load from the ratchet wheels to the worms and allows the scaffold to be lowered. Should it be desirable to stop the downward movement of the scaffold and to. hold same in this position by means of the pawl and ratchet wheel, it isonl necessary to rotate the worms slightly in the opposite direction in order that the pawl may engage the ratchet wheel.

In the drawings, worm wheel 25 is shown as spaced a considerable distance from the ct wheel; a pair 0 side of hanger 11 in order to illustrate the relation of the ratchet wheel, pawl and trip but in practice, worm wheel 25 is disposed as closely as possible to the face of bearing 2* and ratchet wheel 33 is preferably formed on drum 15 instead of on worm wheel 25.

While we have described our invention as taking a particular form, it willbe understood that modifications may be made without departing from the spirit thereof, and

hence we do not limit ourselves to the recise construction set forth, but consider t at we are at liberty to' make such changes-and alterations as fairly come within the scope of the appended claims.

'e claim 1.- A scafl'old'including a frame, a drum 'shaft rotatable in each end of the frame, a

drum on each drum shaft, a worm wheel on each drum shaft, a'worin shaft rotatable in the frame, worms on the worm shaft meshing with the worm wheels, a chain wheel on the worm shaft for rotating said shaft, and separable hinged joints formed in the worm shaft whereby one worm may be rotated inion worms on the worm shaft meshing with the worm wheels, a chain wheel on the worm shaft ,for rotating said shaft, and means. for automatically disengagin the pawls from the ratchetwheels; said isen aging means being actuated by rotating the 0 sin wheel to lower the scaffold. V

'3. A scafiold including a top strut having bifurcated ends, a bifurcated hanger attached to each end of the strut, a hanger bar carried by one hanger, a hen ercable carried by the other hanger, a plat orm support secured to the bar and the cable, a' drum rotatable in the bifurcated end of each hanger, cables for supporti the scaffold windable .on the drums an an overhead support, and drum operating mechanism mounted on the hangers, substantially as described. v

4. In a scaffold raised and lowered by means of a cable wound on a drum secured to a shaft having a worm wheel and a ratchet wheel thereon; ,agiawl en aging the ratchworm bearings secured d; a worm shaft rotatable in to the scafi the bea a worm secured to the shaft and rotatable in the bearings, the worm being shorter than the distance between the ends of the bearings; a trip engaged by the III worm and adapted to engage the pawl whereb *rotation of the worm shaft will cause he worm to move axially and cause the trip to disengage the pawl from the ratchet wheel.

5. A swinging scafi'old includi'n a frame, a drum shaft rotatable in eac end of the frame,'a' drum on each drum shaft, cables windable on the drums and adapted to be secured to an overhead support for suspending the scaffold, a worm wheel on each drum shaft, a worm shaft rotatable in the frame, bendable joints in the worm shaft,

worms on the worm shaft meshing with the worm wheels, :1 chain wheel on the worm shaft for rotating said shaft, means for locking the drums against rotation in one direction, and means, for automatically releasing the locking means; said releasing means being actuated by rotating the chain wheel to lower the scaffold.

In testimony whereof we have signed our names to this specification.

CHARLES tA'Motm. FRANK HOFFMANN. 

